Bollettino valanghe

Silver Valley & Bitterroot Mountains

Idaho Panhandle Avalanche Center
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Pericolo valanghe

Sat
Alta quota
1 · Debole
Limite del bosco
1 · Debole
Sotto il limite
1 · Debole
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Non aggiornato — questo bollettino è scaduto 4 years ago. Stai vedendo condizioni passate, non il bollettino in corso.

In sintesi

The possibility of wet loose avalanches and cornice falls may increase on south aspects from midday onward if direct sun and warm temperatures weaken the snowpack. If you notice signs that the snow surface has become wet and unstable, such as boot penetration past your ankles, then it’s time to move off, and out from below, avalanchable terrain and cornices. More stable and better riding may be found on shaded north aspect slopes.

Problemi valanghivi

  • Loose Wet

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Possible
    Dimensione
    1–2

    Freezing, or near freezing temperatures since Wednesday evening locked the upper snowpack into a hard supportable crust. However, temperatures are forecast to reach the high 30’s to low 40’s today, warm enough for wet loose avalanches to be a concern if the sun peaks out and helps breakdown the surface crust throughout the day. Boot penetration beyond mid-boot is a sign that the upper snowpack is wet and it’s time to move away from weakening avalanchable terrain. More stable slopes may be found on shaded north aspects.

    Roller Balls

  • Cornices

    • Alta quota
    • Limite del bosco
    • Sotto il limite del bosco
    Probabilità
    Unlikely
    Dimensione
    1–2

    The cooler temperatures over the past 36hrs were not likely enough to refreeze moisture deep in the root of large cornices. As temperatures rise again today, so will the danger of cornice falls. Cornices may break further back than you expect, so give them a wide berth on ridges, and avoid traveling beneath them during from midday onward. Debris from cornice falls can be large and hard, and they may trigger avalanches.

    (3/31/2022)

    Cornice Fall Debris

Avalanche Discussion

Warm temperatures over much of the last week infused the upper snowpack with liquid water. Freezing, or near freezing, temperatures returned to the forecast area beginning Wednesday evening, hardening the upper snowpack into a supportable crust. Today, with temperatures forecast to reach near 40F, we should see a return to the spring diurnal freeze/thaw cycle. Wet loose avalanche and cornice fall danger will peak with the warmest temperatures in the early afternoon.

Timing is key during spring skiing as the best riding will be had midday on solar aspects as the crust begins to soften, but before the upper snowpack becomes saturated and weak. If you see signs of wet avalanche problems, boot penetration or steep slopes starting to sluff, be prepared to move to shaded north aspect, or pack it up and head home.

Yesterday I did find reactivity on a layer buried 35cm from the surface in Compression Tests and an Extended Column Test (ECTP25) on a north aspect at 6,600ft on Tiger Peak. Although I think the likely hood of a failure on this layer is very low due to the bridging strength of the surface crust and penetration of moisture in the snowpack, it shows that distinct layers and complexities are still preserved within the snowpack. Full spring conditions, and snowpack uniformity, have not arrived yet.

Looking ahead through the weekend, the diurnal freeze thaw cycle looks like it will continue, so plan your days accordingly. One inch of snow is in the forecast for Saturday, followed by more snow and strong winds Monday and Tuesday.

Regioni coperte